Recently, Fe-Cr-Al alloys have become used more and more in heat resisting applications, such as an outer smoke pipe of an oil stove, an electric heater and a metallic carrier for an automobile catalyst, because of their excellent oxidation resistance.
It is known that oxidation resistance of this alloy is enhanced with increase of Cr and Al concentrations, and that a remarkable improvement in the adhesion of an oxide film serving to maintain the heat resistance can be attained by the addition of a small amount of at least one rare earth element, including Y, to the alloy. For this reason, in recent years, cold-rolled steel products or foil materials have been produced wherein the Cr and Al concentrations were maximized within such a range that the materials are still rollable and, at the same time, rare earth elements including Y were added.
These alloys, however, had a drawback that the producibility of the products from these alloys is poor and the yield decreases with an increase in the heat resistance. In particular, regarding alloys containing rare earth elements including Y, scabs are likely to occur on the surface of steel sheets in the step of hot rolling or cold rolling. The formation of the scabs incurs an increase in the cost of the process for removing the scabs and, in addition, causes a remarkable lowering in the yield.
An object of the present invention is to avoid scabs generation in the step of hot rolling or cold rolling of an Fe-Cr-Al alloy steel having high Cr and Al concentrations with rare earth elements including Y, thereby providing an Fe-Cr-Al alloy steel sheet capable of inhibiting the lowering in yield.